Electric brake.



W. F. MOODY.

ELECTRIC BRAKE. APPLICATION FILED 111.1120, 1910.-

Patented Jul 25, 1911.

2 BHEETSSHEET 1.

INVENTOR MUM/(1177700611 B y WITNESSES:

ATTORNEYS COLUMBIA PLANDGRAFH CO. WASNIN W; 1". MOODY. ELECTRIC BRAKE.

APPLICATION FILED MAY 20, 1910. 998,976. 1 Patented July 25, 1911.

- 2 SHEETS-SHEET 2.

ATTORNEYS UNITED STATES WILLIAM FORD MOODY, OF DENVER, COLORADO.

ELECTRIC BRAKE.

To all whom it may concern:

Be it known that I, XVILLIAM F. MooDY, a citizen of the United States,and a resident of Denver, in the county of Denver and State of Colorado,have invented a new and Improved Electric Brake, of which the followingis a full, clear, and exact description.

My invention relates to electric brakes of the kind provided with aflexible brake band, my more particular purpose being to pro vide inconnection with the band a rocking member so arranged that its ends areconnected with the ends of the brake band and the braking force isapplied to its middle portion, so that when the brake is set theposition of the rocking member is changed by the tension of the brakeband; one end of the rocking member acts for the moment as a fixed pivotand the opposite end pulls upon the opposite end of the brake band, sothat the rocking member operates as a lever of the third class andapplies the braking force most effectively, and with the leastexpenditure of power.

My invention further comprehends mechanism for rendering the action ofthe looking member reversible so that the advan tages of the brake aresecured, no matter whether the rotation of the revoluble me1nher to beoperated upon be in either of two directions, the principle of the brakebeing thus rendered applicable for use in connection with elevators,hoisting machinery, and in fact in all relations where a revoluble shaftturning in both directions is employed in connection with a brake.

My device is adapted for use with brakes employing either direct oralternating current, and for making this point clear 1 show and describeone form of the invention suitable for use with direct current andanother form more particularly adapted for alternating currents, themechanism being so arranged as to greatly reduce the first cost of thebrake and also (which is highly important in alternating currentpractice) to reduce the current consumption. In the devices shown thebrake is applied by opening the main circuit, thereby deenergizing themagnet in the manner well known in this art.

Reference is to be had to the accompanying drawings forming a part ofthis speciiication, in which similar characters of ref erence indicatecorresponding parts in all the figures.

Specification of Letters Patent. Patented July 25, 1911.

Application filed May 20, 1910. 1

Serial No. 562,551.

Figure 1 is a side elevation showing one form of my improved electricbrake which in this instance is suitable for use in connection withdirect currents; Fig. 2 is an enlarged section on the line 22 of Fig. 1,looking in the direction of the arrow; Fig. 3 is a view partly inelevation and partly in section, showing another form of my improvedbrake which, in this instance, is built for use with alternatingcurrents; and Fig. 4 is a fragmentary side elevation of the mechanismshown in Fig. 3.

At 5 is a pulley which is mounted upon a revoluble shaft 6.

At 7 is a magnet and movable relatively to the same is an armature 8carried upon a stem 9. The magnet 7 is provided with a spring case 10having a compartment 11 therein. A disk 12 is mounted rigidly upon thestem 9 and is adapted to move within the compartment 11. A spring 13 ishoused within this compartment and presses upon the disk 12. A closurering 14 presses upon the spring 13 and engages the top of the springcase 10. The stem 9 is provided with a head 15 which supports a yoke 16.

At 17 is a guide strip which is connected by bolts 17 with the magnet,this guide strip being provided at its top with a slot 18. The yoke 16is provided with pins 19, 20 extending directly outward in oppositedirections, the pin 19 being longer than the pin 20 and extendingthrough the slot 18.

At 21, 22 are a pair of rocking bars which are ournaled upon the pins19, 20.

A brake band 28 encircles the pulley 5 and is connected with pins 24,25, the latter being carried by the ends of the rock ing bars andpivotally connected with the respective pins 26, 27 which extend throughears 28, 29 carried by the magnet. Cotter pins 30, 31 extenddiametrically through the guide pins 26, 27 and are adapted to lodgeagainst the ears 28, 29. The pin 30 lodges against the ear 28 when therocking bars are rocked in a clockwise direction according to Fig. 1,and the cotter pin 31 lodges against the ear 29 whenever the rook- 1 ofthe spring 13. It will be noted from the construction, however, thatwhen the magnet shown in Figs. 1 and 2 is deenergized, so that thearmature 8 is, under action of the spring 13, forced downwardly so thatthe pins 19, 20 are lowered, the rocking bars 21, 22 are neverthelessfree to rock a little in a direction which coincides with the directionof rotation of the pulley. Suppose, then, that according to Fig. 1 thepulley 5 is turning in a clockwise direction, and that the magnet 7 isdeenergized. The brake band being tightened a little, the guide pin 26is drawn upward until the cotter pin 30 lodges against the under side ofthe car 28. The pivot pin 24 thereupon beconies in effect a fixed pivotfor the rocking bars 21, 22, the opposite ends of these rocking barsbeing free relatively to the car 29, and the cotter pin 31 being in itslowermost position, considerably out of engagement with the ear 29. Itis clear, then, that the rocking bars 21, 22, together act as a lover ofthe third class and pull directly upon the right hand portion of thebrake band according to Fig. 1. The braking action is thus rendered veryeffective and is moreovc accompanied by a comparatively slightexpenditure of energy. Suppose, however, that the rotation of the member5 is in the opposite direction-that is, in a counterclockwise directionaccording to Fig. 1. The braking action is thereupon just reversed, thepivot pin 24 moves downwardly. The brake thus described is thereforeapplicable to mechanism in which the direction of rotation isreversible. The braking force is applied midway between the ends of therocking bars, no matter what may be the direction of rotation of themember to be braked.

In the mechanism shown in Figs. 3 and 4 the pulley is shown at 32, themagnet at 33 and its winding at 33. Supporting this magnet is a casing34 and movably mounted within the bottom of this casing is an armatureGuide pins 36 are connected rigidly with this armature by aid offastening members 37. Encircling the guide pins 36 are spiral springs 38which normally tend to lower the armatures relatively to the casing andmagnet. A beam 39 is connected with the pins 36 by aid of nuts 39 and39". At 40 is the brake lever which is provided with bearings 40 and byaid thereof is mounted to rock upon a pivot pin 41. A brake band 42 isconnected with pins 43, 44 carried by the outer ends of the brake lever.Guide pins 45, 46 are journaled upon the pins 43, 44 and extend throughears 49, 50 which serve as guides. The guide pins 45, 46 are providedwith holes 47 through which extend cotter pins 48.

The operation of the mechanism shown in Figs. 3 and 4 is very much likethat above described with reference to the other figures. The tendencyof the springs 38 being to force the armature 35 downwardly, the settingof the brake is accomplished by deenergizing instead of by energizingthe magnet 33. The magnet beingdeenergized and the armature 35 beingforced downwardly, the beam 39 and the rocking lever 40 are alsolowered. The brake band being tightened slightly, the guide pin 45 or46, as the case may be, is drawn upwardly until its cotter pin stopsagainst the under side of the adjacent ear 49 or 50, after which thebrake lever 40 swings upon practically a fixed pivot, the direction ofthe rocking movement of the brake lever coinciding with the direction ofrotation of the pulley to be braked. The form of brake shown in Figs. 3and 4 embodies all of the advantages above described with reference tothe brake shown in Figs. 1 and 2.

It will be noted that in both of the mechanisms above described,whenever one end of the brake lever becomes fixed, so that the leveroperates practically upon a fixed pivot, the opposite or free end of thelever is at the so-called slack end of the brake band; that is to say,that portion of the band where the tension is the smallest. There isconsiderable advantage in this arrangement and this advantage manifestsitself as above stated both in the original cost of the brake and in thesaving of current. In many instances, especially where alternatingcurrent is applied, a considerable amount of energy must be expended inconnection with the brake. Moreover, the constant opening and closing ofthe circuit controlling the brake, is necessarily a disturbing factor,which is reduced to a minimum by this arrangement which calls for theuse of comparatively little current. The excessive current demanded forreleasing brakes operated by magnets or solenoids, is oftentimes aserious strain upon the generators or transformers from which thecurrent is derived. This is especially true of residence districts wherethe custom is to install transformers not especially adapted for takingcare of irregularities in the current due to the opening and closing ofthe various circuits. In instances of this kind, where for a momentthere is a considerable rush of current in excess of the regular demand,there is a corresponding drop in the voltage and a serious decline inthe energy of the motor operating the machine to which the brake isconnected, as well as other motors in the neighborhood. In one instanceof this kind it happens that a ten horse power motor operating on analternating current circuit, required a momentary rush of 2700 watts toproduce a given braking effect when the same effect was secured for asimilar installation operating on direct current by an expenditure ofonly 300 watts. Taking into consideration facts of this kind, it isobvious that any device capable of reducing the total mechanical efiortnecessary for braking must result in a corresponding decrease in thedisturbance of the circuit (and especially if alternating currents beused) on which the brake is employed.

The reason why the form shown in Figs. 1 and 2 is suitable for directcurrent and that appearing in Figs. 3 and 4: is better for alternatingcurrents, is traceable to the fact that alternating currents are, ifused in proximity to bodies of iron, wasteful of energy unless saidbodies of iron are laminated or otherwise prevented from setting up eddycurrents. Referring now to the bottom of Fig. 8, it will be noted thatthe core of the magnet 33 is made up of E-shaped stampings, which is notthe case with the core shown in Fig. 2. The E-shaped stampingsconstitute laminations which, by preventing the undue formation of eddycurrents prevent waste of the alternating currents used for energizingthe magnet 38.

IVith my improved brake above described, the energy required to producea given braking effect, is a great deal less than would be the case ifthe pull exerted by the spring were transferred to the other, hightension, end of the band, without changing the direction of rotation ofthe shaft to which the braking action is applied.

I do not limit myself to the precise details of construction hereinshown and described, nor in all instances to the exact arrangement setforth for the various parts, the scope of my invention beingcommensurate with my claims.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. In a brake, the combination of a brake band for encircling arevoluble member, a rocking lever having its ends connected with theends of said brake band, a fixed magnetic member, an armature therefor,said armature being free to move toward and from said revoluble member,a frame mounted rigidly upon said armature and movable directlytherewith toward and from said revoluble member, said frame beingjournaled to said lever at a point intermediate the ends of said brakeband, and spring mechanism for moving said armature in a directioncontrary to the direction in which said armature is attracted by saidmagnetic member.

2. In a brake, the combination of a casing, guide pins slidably engagingthe same, an armature carried by said guide pins, a magnetic membermounted Within said casing and adapted to move said armature in onedirection by attraction, springs encircling said guide pins and engagingsaid casing and said armature for moving said armature away from saidmagnetic member, a beam supported upon said guide pins and by aidthereof movable with said armature, a brake lever ournaled upon saidbeam and adapted to rock, and a brake band for encircling a revolublemember, said brake band having its ends connected with the ends of saidbrake lever.

3. In a brake, the combination of a brake band for encircling arevoluble member, a brake lever connected with the ends of said brakeband, mechanism including a member journaled to said brake lever forshifting said lever in order to aid in setting and releasing said brakeband, guide pins pivotally mounted adjacent to the ends of said brakeband, and means for limiting the travel of said guide pins.

4. In a brake, the combination of a brake band for encircling arevoluble member, a brake lever having its ends connected with the endsof said brake band, a beam journaled to the proximate middle of saidlever and adapted to move bodily toward and from said revoluble member,guide pins connected With said beam, an armature mounted upon said guidepins, a magnetic member for attracting said armature, and springmechanism for retracting said armature.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WILLIAM FORD MOODY. lVitnesses SAMUEL H. BAKER, J. P. MOODY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of- Patents, Washington, D. G.

